1. Field of the Invention
The invention relates to a clip that is attached to a member to be mounted (for example, a plate or the like, especially, a cover such as an undercover for a vehicle) and that brings a screw member into an engaged state by insertion of the screw member into an insertion hole formed in the clip.
2. Description of the Related Art
For example, it has been found that mounting an undercover (a member to be mounted) on the underside of a vehicle body (a target member on which the undercover is mounted) improves the aerodynamic performance of the vehicle and hence the fuel efficiency thereof. Specifically, a cylindrical clip made of synthetic resin is attached to the undercover, a screw member extending upward from the vehicle body is engaged with the clip, and thus the undercover is attached to the vehicle body. Such a clip includes a tubular body part with an insertion hole for the screw member, and elastic locking pieces. The elastic locking pieces are located in predetermined opposite areas on the inner periphery of the insertion hole with the axis of the screw member, inserted into the insertion hole, between them. The elastic locking pieces extend from a first side in the axial direction of the inserted screw member to a second side in the axial direction thereof, which is opposite to the first side, such that the leading end of each elastic locking piece approaches and engages with the screw member. Each elastic locking piece is elastically deformable so that its leading end separates from the screw member.
Some of these clips are engageable with a plurality of types of screw members different in screw groove pitch as described, for example, in Patent Document 1. Specifically, in such a clip, each of the opposite elastic locking pieces as described above has, at its leading end, engaging claws that engage with a helical screw groove in the outer periphery of the screw member, and the engaging claws are formed such that even where at least two or more types of screw members respectively different in screw groove pitch are inserted into the insertion hole of the tubular body part, the engaging claws are engageable with the screw groove of the screw member.
However, in a clip formed so as to cope with the respective pitches of a plurality of types of screw grooves, there is a demand to further improve the load that is able to be supported by the clip's engagement with each of the respective grooves of those screws. That is, such a clip is formed so as to match the respective predetermined pitches of a plurality of screw grooves. Therefore, if a screw member is used, engagement with which is slightly off, supporting force in the axial direction for the screw member resulting from engagement may decrease. To improve the supporting force, a change to a more expensive material may be proposed. However, a cost increase is not desirable.